
\begin{tabular}{rrrrrrr}
\toprule
\multicolumn{1}{c}{ } & \multicolumn{3}{c}{BRS} & \multicolumn{3}{c}{QCA} \\
\cmidrule(l{3pt}r{3pt}){2-4} \cmidrule(l{3pt}r{3pt}){5-7}
N & Num. Rules & Rule Len. & Accuracy & Num. Rules & Rule Len. & Accuracy\\
\midrule
25 & 1.51 & 2.30 & 0.90 & 1.93 & 2.34 & 0.93\\
100 & 1.85 & 2.46 & 0.99 & 2.00 & 2.50 & 1.00\\
250 & 2.00 & 2.50 & 1.00 & 2.00 & 2.50 & 1.00\\
500 & 2.00 & 2.50 & 1.00 & 2.00 & 2.50 & 1.00\\
750 & 2.00 & 2.50 & 1.00 & 2.00 & 2.50 & 1.00\\
\addlinespace
1000 & 2.00 & 2.50 & 1.00 & 2.00 & 2.50 & 1.00\\
\bottomrule
\end{tabular}
